1. Field of the Invention
This invention relates to a new water-soluble peptide antibiotic, to methods for its production and isolation, to pharmaceutical compositions containing it and to methods of using said antibiotic as an antimicrobial agent.
2. Description of the Prior Art
The new antibiotic of the present invention is a water-soluble cyclic acyl octapeptide containing D-proline, D-serine, L-proline, L-arginine, D-threo-.beta.-hydroxyaspartic acid, D-serine, L-trans-3-hydroxyproline and L-threo-.beta.-hydroxyaspartic acid and a C.sub.14 fatty acid residue of 3-hydroxytetradecanoic acid. The new antibiotic is produced by fermentation of Empedobacter sp. strain G393-B445 (ATCC 31962).
A literature search carried out on behalf of the present applicants has failed to uncover any polypeptide antibiotics containing the same constitutive amino acids and fatty acid residue as the antibiotic of the present invention (designated by the inventors as Bu-2517). Among the polypeptide antibiotics reported in the literature, however, Bu-2517 has some similarities to amphomycin (Antibiot. Chemother. 3: 1239-1242, 1953; J. Am. Chem. Soc. 95:2352, 1973; U.S. Pat. No. 3,126,317) in its amphoteric nature, to antibiotic BA-843 (Japan Kokai No. 130,601/53; Farmdoc 92052A/51) in the producing organism and some of the constitutive amino acids and to permetin A (J. Antibiotics 32:115-120, 1979; J. Antibiotics 32:121-135, 1979) in the cyclic depsipeptide structure. An amino acid component of Bu-2517, trans-L-3-hydroxyproline, is one of the structural constituents of telomycin (Antibiotics Ann. 1957/1958, 852-855; U.S. Pat. No. 3,016,516). All of the polypeptide antibiotics mentioned above, however, may be clearly differentiated from Bu-2517 in their chemical and biological properties.